1. Field of the Invention
The present invention relates to novel block polymers comprising polyether blocks and oligoamide blocks, also designated block polyetheramides.
2. Description of the Prior Art
Various block polyetheramides are known to this art.
FR 2,273,021 and FR 2,401,947, assigned to the assignee hereof, describe polyetheramides having the formula: ##STR2## in which A is a polyamide block and B an aliphatic polyether block.
These polymers are prepared by reacting, in molten state, a dicarboxylic polyamide having an Mn ranging from 300 to 15,000 with a polyetherdiol having an Mn ranging from 200 to 6,000 in a high vacuum at temperatures ranging from 100.degree. to 400.degree. C., in the presence of one or more metal tetraalkoxides of the formula M(OR).sub.4 as catalyst, wherein M is titanium, hafnium or zirconium and R is a hydrocarbon radical having from 1 to 24 carbon atoms.
These block polyetheramides exhibit good mechanical and chemical properties.
FR 2,384,810 describes polyetheresteramides prepared by polymerization at autogenous pressure and at temperatures ranging from 230.degree. to 300.degree. C. of a mixture of:
(i) one or more polyamide monomers,
(ii) an alpha,omega-dihydroxy(polytetrahydrofuran) or PTMG having an Mn ranging from 160 to 3,000, and
(iii) at least one diacid, in the presence of water; the water is then removed from the reaction mixture, which is then returned to normal or reduced pressure at a temperature ranging from 250.degree. to 280.degree. C.
The products obtained are also block polymers and exhibit good impact strength when cold.
However, polymers prepared from the same polyetherdiol as per the above patents have a lower melting temperature than the below described polymers according to the present invention, at the same hardness.
Moreover, the block polyetheramides according to the invention have a lower rigidity at low temperatures than the block polyetheramides of the same melting point and the same Shore D hardness obtained according to the processes described in FR 2,273,021, FR 2,401,947 or FR 2,384,810.
DE 3,428,405 describes polymers which are similar to such prior art polymers, having improved stability to hydrolysis and which are prepared from a stoichiometric mixture of oligoamidediacid and of oligoetherdiol and from 3% to 30 mol % relative to the mixture of diol of low molecular weight.
J63-048,332 describes block polyetheramides based on nylon salts, in which the compatibility between the rigid segments and flexible segments is improved by incorporating aliphatic diacids into the (flexible) polyetherdiols prior to the time the polyetherdiols thus modified are reacted with the oligoamidediacids. With the same polyamide block, the melting point of these polymers decreases with the hardness and the modulus. Similar polymers are described in J63-227,238 and similar processes in J63-280,736 and J63-105,032.
J63-182,343 describes block polyetheramides prepared by reacting, in the molten state, PA-6,6 blocks having diamine end groups with a polyether having dicarboxylic acid end groups. The melting point of the polymers obtained according to this application varies in the same sense as their flexural modulus and their hardness.